The present invention relates generally to biomedical devices and methods for manufacturing biomedical devices and more particularly to biomedical devices that have full or partial polymer coatings and their methods of manufacture.
Medical instruments are frequently coated with various polymers to reduce sliding friction (e.g. by lubricity) and provide other performance enhancing characteristics. Obtaining adequate adherence of the polymer coating to the instrument substrate is a problem in many instances and particularly when a hydrogel is coated on a metal substrate.
Various hydrophylic and hydrophobic polymer coatings and their methods of application have been described in U.S. Pat. No. 4,263,372 Method of coating and/or impregnating porous substrates, and products obtained thereby (Emmons et al.); U.S. Pat. No. 4,435,476 Method of making an abrasion resistant coating on a solid substrate and articles produced thereby (Phillips et al.); U.S. Pat. No. 4,504,528 Process for coating aqueous fluoropolymer coating on porous substrate (Zucker et al.); U.S. Pat. No. 4,541,980 Methods of producing plastic-coated metallic members (Kiersarsky et al.); U.S. Pat. No. 4,705,584 Application of polymeric materials to substrates (Lauchenauer); U.S. Pat. No. 4,729,914 Hydrophilic coating and substrate coated therewith (Kliment et al.); U.S. Pat. No. 4,784,159 Process for making an implantable device having a plasma sprayed metallic porous surface (Szilagyi); U.S. Pat. No. 5,095,915 Guidewire with flexible distal tip (Engelson); U.S. Pat. No. 5,129,890 Hydrophilically coated flexible wire guide (Bates et al.); U.S. Pat. No. 5,235,964 Flexible probe apparatus (Abenaim); U.S. Pat. No. 5,290,585 Lubricious hydrogel coatings (Elton); U.S. Pat. No. 3,969,552 Process for impregnating porous articles (Malofsky et al.); U.S. Pat. No. 4,147,821 Impregnation of porous articles (Young); U.S. Pat. No. 4,556,701 Impregnate compositions for porous substrates (Schindler et al.); U.S. Pat. No. 5,333,620 High performance plastic coated medical guidewire (Moutafis et al.); U.S. Pat. No. 5,441,488 Medical tool having lubricious surface in a wetted state and method for production thereof (Shimura et al.); U.S. Pat. No. 5,443,455 Guidewire and method of pretreating metal surfaces for subsequent polymer coating (Hergenrother et al.); U.S. Pat. No. 5,443,907 Coating for medical insertion guides (Slaikeu et al.); U.S. Pat. No. 5,437,288 Flexible catheter guidewire (Schwartz et al.); U.S. Pat. No. 5,573,520 Flexible tubular device for use in medical applications (Schwartz et al.); U.S. Pat. No. 5,749,968 Device for priming for improved adherence of gels to substrates (Melanson et al.); U.S. Pat. No. 5,750,206 Method of pretreating metal surfaces for subsequent polymer coating (Hergenrother et al.); U.S. Pat. No. 5,833,632 Hollow guide wire apparatus catheters (Jacobsen et al.); U.S. Pat. No. 5,700,559 Durable Hydrophilic Surface Coatings (Sheu et al.); U.S. Pat. No. 6,080,488 Process for preparation of slippery, tenaciously adhering, hydrophilic polyurethane hydrogel coating . . . medical devices (Hostettler et al.); U.S. Pat. No. 6,149,978 Coating of porous, hydrophobic substrates with thermoplastic fluoropolymers (Bladel et al.); U.S. Pat. No. 6,162,310 Method for producing porous sponge like metal (Tseng); U.S. Pat. No. 6,176,849 Hydrophilic lubricity coating for medical devices comprising a hydrophobic top coat (Yang et al.); U.S. Pat. No. 5,840,046 Guidewire Having Hydrophilic Coating (Deem); U.S. Pat. No. 5,984,878 (Multi-Coating Stainless Steel Guidewire (Engelson) as well as PCT International Patent Publications WO 92/11877 Biocompatible abrasion resistant coated substrates (Fan et al.) and WO 00/65143 Process for coating a perforated substrate (Munro et al.), all f which are expressly incorporated herein by reference.
One reason for applying polymer coatings to insertable medical devices is to impart lubricity to, or to lower the coefficient of friction of, the outer surface of the device. Some of these polymer coatings, such as fluorocarbon coatings (e.g., polytetrafluoroethylene) provide a lubricious hydrophobic surface while others such as swellable hydrogels are hydrophilic and become lubricious after coming in contact with liquid (e.g., blood or other body fluid).
For example, U.S. Pat. No. 5,573,520 (Schwartz et al.) describes a flexible tubular member encased by a fluid tight polymer covering, including a hydrogel, for use as a guidewire, catheter or introducer. However, the polymer covering is only described as covering either the inside surface or the outside surface for the purposes of a fluid tight sealing of aperatures or for providing lubricity. As described earlier, these benefits of coatings are known in the art. However, Schwartz et al. does not describe the coating to be integral to the wall of the device or there being any sort of interlock or other improved attachment of the coating.
Also, U.S. Pat. No. 5,840,046 (Deem) describes guidewires having hydrophilic coatings, such as hydrophilic polysaccharides (e.g., hyaluronic acid or chondroitin sulfate). The guidewires are made of wire which is helically coiled about a core member. The spacing between adjacent coils of the wire is wide enough to allow the coating to flex along with the coil but narrow enough to prevent the coating from penetrating into an annular space that exists between the coiled wire and the inner core member.
The present invention provides novel polymer coated medical instruments including guidewires, catheters, cannula, endoscopes and other instruments for insertion into the body.
In accordance with the present invention, there are provided medical devices that are insertable into the bodies of human or veterinary patients, each such device comprising a) a working element having an outer surface and b) a polymer coating disposed on at least a portion of the outer surface of the working element, wherein the outer surface of the working element has a topography characterized by surface features which deter longitudinal slippage of the coating over the outer surface and or which result in some mechanical engagement or interlock between coating and the working element. In this regard, the outer surface of the working element may have one or more cavities formed therein, at least some of those cavities having side walls which are disposed at angles of about 75 or more degrees relative to the longitudinal axis of the working element (or relative to the outer surface of the working element immediately adjacent to those side walls) and wherein at least a portion of the polymer coating extends into at least some of the cavities so as to deter separation of the polymer coating from the working element. In this manner the present invention may provide an alternative to the use of adhesive coatings or chemical adhesive layers such as the xe2x80x9ctie layersxe2x80x9d described in U.S. Pat. No. 5,749,837 (Palermo), which is expressly incorporated herein by reference.
Further in accordance with the invention, the cavities formed in the outer surface of the working element may comprise holes, grooves, a continuous helical or curved groove, slots, pores, apertures or other external surface features to provide a substantial improvement in the adherence of a polymer coating. The coating fills into at least some of the cavities to form a mechanical bond or interlock with the working element. To accomplish such mechanical bond or interlock, the cavities are preferably at least about 0.001 inch deep and may extend completely through the working element forming a through-hole or slot. In at least some embodiments, it is preferable that the polymer coating to penetrate to a depth below the outer surface that is at least about 25%, and more preferably at least about 50%, of the total thickness of the polymer coating on that portion of the device. Thus, for example, in a region where the polymer coating is a total of 100 mills thick, it will be preferable for the coating to penetrate into cavities at least about 25 mills below the outer surface and more preferably at about 50 mills below the outer surface. The coating need not be for the purpose of providing lubricity, although such is one purpose for the invention. Indeed, the coating may serve any purpose, such as the creating of a biocompatible barrier to insulate the patients body from toxic, infectious or non-biocompatible materials on the underlying surface of or within the device.
Still further in accordance with the invention the working element may comprise any apparatus or device that is insterable into the body, including but not limited to a wire, a guidewire, a tube, a catheter, a cannula, a scope (e.g., rigid or flexible endoscope, laparoscope, sigmoidoscope, cystoscope, etc.) a probe, an apparatus for collecting information from a location within the body (e.g., an electrode, sensor, camera, scope, sample withdrawal apparatus, biopsy or tissue sampling device, etc.). The working element""s outer surface may be made from a radiopaque, biocompatible metal such as platinum, gold, tungsten, nitinol, elgiloy, stainless steel, or tantalum but may be made of a polymer impregnated or otherwise modified to be visible under x-rays by various means known in the art. Alternatively, the working element""s outer surface may be made of a plastic or polymer material which, in at least some embodiments, may be visualized under ultrasound, magnetic resonance imaging, radiographic imaging or other medical visualization methods known in the art.
Still further in accordance with the present invention, the polymer coating may comprise a material that is lubricious or has a low coefficient of friction, such as polytetrafluoroethylene (e.g. Teflon). Also, the polymer coating may comprise a hydrophilic polymer (i.e. hydrogel) that creates a lubricious surface after being exposed to a liquid (e.g., blood or other body fluid). It is preferable that the hydrogel be polymerized from ethylenically unsaturated monomers. In some cases, environmentally responsive hydrogels may be used such as that described in cozening U.S. patent application Ser. No. 09/804,935 entitled Hydrogels That undergo Volumetric Expansion In Response To Changes In Their Environment And Their Methods Of manufacture And Use. Specific examples of hydrogels that may be used include those described in U.S. Pat. No. 4,729,914 (Kliment), U.S. Pat. No. 5,290,585 (Eiton), U.S. Pat. No. 5,331,027 (Whitboume), U.S. Pat. No. 6,080,488 (Hostettlerel al.), U.S. Pat. No. 6,176,849 (Yang et al.) and pending U.S. patent application Ser. No. 09/804,935 entitled Hydrogels That undergo Volumetric Expansion In Response To Changes In Their Environment And Their Methods Of manufacture And Use, each of which is expressly incorporated herein by reference. In some embodiments of the invention, the polymer may be formed about the outer surface of the working element in a non-continuous manner (e.g., in discrete ridges, bumps or areas) or such polymer coating may be disposed in a manner that forms a generally smooth continuous polymer coating surface. In some embodiments, the polymer coating may be radioopaque.
Even further aspects of this invention will be come apparent to those of skill in the art upon reading of the detailed description of exemplary embodiments set forth herebelow.